Recently, electronic parts such as capacitors have been required to be small-sized, accompanying with miniaturization of electronic equipments. Accordingly, respect to film capacitors, so-called chip capacitors applicable with surface mounting have been developed. So-called stacking type film capacitors, wherein substantially planar and rectangularly cut dielectric films and electrodes such as deposited metal layers are stacked, are particularly favorable for miniaturization. In such a small-sized stacking type film capacitor, since usually a thin film is used as its dielectric film, the capacitance generating portion of the capacitor is likely to be injured. Therefore, a protective layer formed by stacking thick films or sheets is provided on the outer side of the capacitance generating portion of the conventional film capacitor in order to protect the capacitance generating portion. In a chip capacitor, however, although a high thermal resistance for soldering is required for the protective layer because the capacitor is soldered directly to a printed circuit board, a protective layer having an excellent thermal resistance cannot be obtained by the conventional process wherein the protective layer is formed by stacking thick films or sheets.
In more detail, it is considered that a film having a high thermal resistance such as a heat sticking type polyimide film or a biaxially oriented polyphenylenesulfide film is used to form a protective layer having a high thermal resistance. However, there are defects in the polyimide film that the film is expensive and has a poor chemical resistant property, the deterioration of the film due to hydrosis under a high moist condition quickly occurs, and the dimensional stability of the film against moisture is poor. As a result, the environment for use of the film is restricted. In ordinary biaxially oriented polyphenylenesulfide films, according to the investigation by the inventors of the present invention, the films are easily delaminated between the film layers because the adhesive property between the film layers is not good. Therefore, a practical protective layer cannot be obtained. Further, although it is considered that a film, in which an adhesive is applied onto or a layer having an adhesive property is provided on a biaxially oriented polyphenylenesulfide film, is used (for example, JP-A-SHO 64-77910), a process for applying the adhesive must be added, and the process for producing the capacitors becomes complicated by the application process. Moreover, because the biaxially oriented polyphenylenesulfide film slightly shrinks accompanying with a large shrinkage stress when the film is heated such as when the capacitor is attached, if a usual adhesive is used, the deformation or delamination of the protective layer occurs, for example, when the capacitor is dipped in a molten solder. Therefore, a practical protective layer also cannot be obtained.